Why do you want to take a backup outside of the FRA ?, its better to keep it inside.
Anyway try this:
configure controlfile autobackup format for device type disk to '/inst/BACKUP_DATABASE/controlfile/%F.ctl';
allocate channel dup1 device type disk;
sql "create pfile=''/inst/BACKUP_DATABASE/pfile/initpfile.ora'' from spfile";
backup format '/inst/BACKUP_DATABASE/hot_db/hot_bkp_%U' database;
release channel dup1;
backup incremental level 0 as compressed backupset format '/inst/BACKUP_DATABASE/hot_db/hot_bkp_%U' database plus archivelog delete all input;
Change it to fulfill your requirement, this is only an example.
I hope this help you
We are only doing this to save space. Archive logs and every other auto backup with flashback logs are going to the FRA.. Getting an error?
RMAN> backup incremental level 1 CUMULATIVE as compressed backupset TAG 'geohubpr_L1_db' format '/mnt/san/odanfs/rman_backup/%D_%U.bak';
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00558: error encountered while parsing input commands
RMAN-01009: syntax error: found ";": expecting one of: "archivelog, as, auxiliary, backupset, backup, channel, check, controlfilecopy, copies, copy, cumulative, current, database, datafilecopy, datafile, db_file_name_convert, db_recovery_file_dest, device, diskratio, duration, filesperset, force, format, for, from, full, incremental, keep, maxsetsize, nochecksum, noexclude, nokeep, not, pool, proxy, recovery, reuse, section, skip readonly, skip, spfile, tablespace, tag, to, validate, comma, ("
RMAN-01007: at line 2 column 132 file: standard input